1. Field of the Invention
This invention relates to improved clutter processors for the detection of objects such as radar targets and particularly to a detection arrangement that utilizes an adaptive threshold based on time samples instead of space samples.
2. Description of the Prior Art
Conventionally, adaptive radar clutter thresholding devices sample clutter video from different positions in space, area or range. These clutter video samples are averaged to estimate the mean value and the threshold is based on the multiple of the sample mean. The widely used mean level detector utilizes this technique to establish an adaptive detection threshold in radar clutter video which gives good performance and a constant false alarm rate for clutter with a Rayleigh probability density function. Thus, for example the mean level detector is effective in sea clutter but in the presence of ground clutter, which is not Rayleigh distributed and contains many high amplitude clutter returns, the threshold is raised and the detection sensitivity is decreased. Various types of clutter discrimination techniques include manual rejection of clutter on a selected area basis, automatic rejection of stationary clutter based on scan to scan correlation in a digital clutter map and use of a track while scan function to track clutter returns and reject them based on a velocity criterion. All of these methods have limitations in the presence of certain type of clutter conditions with manual rejection placing a heavy work load on an operator for dynamic clutter environments, automatic clutter mapping having limitations against scintillating or fading clutter and clutter tracking being vulnerable to saturation of the computer time and core capacity when operating in high density clutter. A detector system that is relatively insensitive to the presence of rapidly changing high clutter amplitude peaks would be of a substantial advantage to the art especially in the presence of ground clutter.